Radio receiving system



Nov. 13; 1934. I M. B. BENSON 1,930,713 RADIO RECEIVING SYSTEM v Filed July 30, 1930 4 Sheets-Sheet 1 INVENTOR' ATTORN EYS Nov. 13, 1934. I M. B.BEN$ON 1,930,713

1 RIKDIO RECEIVING SYSTEM Filed July 30, 1950 4 Sheets-Sheet 2 INVENTOR Mali 121251 6mm /5 BY 54 CM/z} ATTORNEYS NOV. 13, 1934. MDB BENSON 1,980,713

- RADIO RECEIVING SYSTEM Filed July 30, 1930 4 Sheets-Sheet 3 INVENTOR ATTORNEYS Nov. 13, 1934. I BENSON 1,980,713

,RADIo RECEIVING SYSTEM Filed July 30, 19 30 4 Sheets-Sheet 4 INVENTOR TORNEYS Patented Nov. 13, 1934 UNITED STATES RADIO RECEIVING SYSTEM Melvin B. Benson, New York, N. Y., assignor, by mesne assignments, to Melvin B. Benson Corporation and Melvin B. Benson Application July so, 1930, Serial No. 471,686

4 Claims.

This invention relates to the detection, amplification and reproduction of sounds in radio broadcasting and the like. i

The object of the invention is to provide an .5 electric circuit for the detection, amplification and reproduction of radio frequency signal system including means whereby the regulation, adjustment and tuning of the circuit are simplifi ed and facilitated and whereby a more accurate reproduction of the sounds is obtained. A further object of the invention is a circuit including means whereby inductances and capacities may be varied simultaneously while maintaining the exact and required proportions desired between them. A further object of the invention is a radio circuit variable in inductance, capacity and resistance at will with the inductances, ca-

pacities and resistances combined in single unitarycoils whereby the variation of one effects the variation of the other factorssimultaneously and proportionately, and to this end the combined inductance, capacity and resistancecoils are wind able and unwindable upon drums or the like, one

a short circuiting drum and the other a variable inductance and capacity drum, the drums being rotated simultaneously to effect the simultaneous variation in values and proportions. Further objects of the invention will hereinafter appear.

For a better understanding of the invention reference may be had to the accompanying drawings wherein: I

Fig. 1 is a diagrammaticillustration of one embodiment of the invention,

Fig. 2 is a diagrammatioview illustrating another embodiment, g

I Fig. 3 is a View illustrating a further embodiment,

Fig. 4 is an end view illustrating one embodiment of the drums, 40 Fig. 5 is a plan view-of the apparatus indicated inFig. 4,

Fig. 6 shows a modified form of drum, and Fig. 7 is a sectional view along the line 7-7 of Fig. 6.

,45 1,.- Referring to Fig. 1 of the drawings I have illustrated a radio receiving and reproduction circuit including an aerial 1, a loud speaker 2, a detector 4, a radio frequency amplifier 3, a transformer 5 and an audio frequency amplifying tube 6. I have indicated at 7 a, radio frequency transformer primary and at 8 the secondary of the transformer. These coils 7 and 8 are windable and unwindable about drums 9 and 10 to vary simultaneously the inductances andcapacitiesthereof. The same primary and secondary coils 7 and 8 are windable about the drums 9' and 10' for the purpose of varying the impedance thereof simultaneously with the variations in inductances andcapacities. The amplifying tube 3 is, of course, connected across the secondary drums 10 and 10' with the grid connected through the conductor 11 leading to a brush 12 in contact with a contact ring 13 upon the drum 10, one end 8' of the coil being electrically connected with this contact ring 13. The filament side of the tube 3 is connected through a conductor 14 with a brush 15 in electrical communication with the drum 10' forming the grid return. The drum 9' is connected through a brush l6 and conductor 17 to the ground. Both drums 9 and 10 are drums for short circuiting the bare wire of coils 7 and 8 as these coils are unwound from the drums 9 and 10 and wound upon the drums 9 and 10'. The drums 9 and 10 as will be more specifically described later in connection with Figs. 4 and 5 are so constructed as to vary the impedance of the circuit of coils 7 and 8 as they are wound and unwound upon the drums 9 and 10, the total effect of the drums 9 and 10 and 9' and 10' being to vary the resistance, inductance and capacity of the circuit simultaneously with any rotation of the drums, and moreover in the exact relative proportion or ratio desired.

The plate of the amplifier 3 is connected through a conductor 18 and brush 19 with a coil 7 windable and unwindable about a second drum 9, the connection beingthrough a brush 19 in contact witha metallic ring20 to which the end 21 of the coil 7 is electrically attached. The other endof the primary coil 7 iswindable about a drum .9.for the purpose of short circuiting the conductor of coil 7 as the latter is wound therear'ound and the drum 9' is connected through a brush 22 and a conductor 23 with the B battery terminal. The secondary coil 8, correspondingtothe coil 7, is wound about the drum 10 similarly to that described'above with reference to the grid circuit of the amplifier 3 and the coil 8 is similarly wound about a short circuiting drum 10'. The coil 8 is connected through the brush 12 and conductors 24 and 25 with the detector tube 4, a grid capacity 26 and grid resistance 27 being connected in the circuit of conductors 24 and 25. The other end of the coil 8 is 5 connected through the brush 1.5 with a C battery 28 and thence to the terminal 29 and a conductor 30 to the detector tube 4. For feed back or regenerative purposes a combined variable inductance and capacity coil 31 is wound about a 11 drum 32, one terminal 31 of the coil 31 being connected with the contact ring 33 of the drum 32 and the latter being engaged by a brush 34 which is connected through a conductor 35 with the anode plate of the tube 4. The other end of the coil 31 is connected with the short circuiting drum 36 which is in turn connected through a brush 37 and a conductor 38 with one coil of the transformer 5. The other coil of the coupling transformer 5 is connected with the tube 6 through conductors 38 and 39, while" the anode plate of the tube 6 is connected through a conductor 40 with the loud speaker 2, the other terminal of the speaker being connected with the plus side of the B battery. The A and B batteries are omitted for convenience in illustration, but the terminals are marked with the letters A and B as indicated.

The preferred form of construction of the drums is illustrated in Figs. 4 and .5. For example, I have shown the drum 10 as comprising a spiral insulated groove 41 on its cylindrical surface for the accommodation of the flexible conductor 42 going to make up the coil 8. This drum may be made of an insulating material as for example bakelite or it may be made of metal with the exterior grooves insulated. Surrounding the drum and coil 8 is a cylindrical metallic capacity plate 43, this being stationarily mounted in any convenient manner, as for example upon a pedestal 45. It is provided with a slot 44 on one side to permit the flexible conductor 42 to be wound upon and from the drum 10 as the latter is rotated in adjustment. The drum 10' may be made of any suitable material, as for example metal to provide for short circuiting the conductor 42 asthe latter is wound thereupon, or it may be made of insulating material with a metallic plate for short circuiting the conductor wire 42. The conductor 42 is indicated as having its terminal 42' attached to the drum 10. The coil 8 thus serves as one capacity plate while the plate 43 serves as the other plate, and since the capacity is to be connected up as usual across the input transformer or inductance coil it is only necessary to connect the plate 43 to one side of the coil, the coil already being connected in circuit. In Fig. 4 I have shown the plate 43 connected to the brush 15 of the short circuiting drum by a wire 105. The other drums of the system of Fig. 1 are of similar construction and need not be described. The drums 9 and 10 and 9' and 10' are mounted for adjustment in unison as are also the set of drums 9, 10, 32 and 9, 10 and 32' and any suitable means may be provided for rotating these drums. The system shown is particularly adapted for use in short wave systems though certain features thereof are applicable to other systems. By this system the adjustment and tuning in may be readily and accurately effected, the refinement in adjustment being practically unlimited. Moreover the inductances and capacities are varied in the exact desired proportions with respect to each other thereby also facilitating accurate adjustment and tuning.

At 46 I have indicated loading coils for introduction into the circuits 11 and 24 to shift the frequency band of the system, couplings 47 being provided for this purpose.

' In Fig. 2 I have shown my invention as incorporated in a straight tuned radio frequency circuit feeding into a non-regenerative detector and including a two stage radio frequency amplifier and a single stage audio frequency amplifier. In this system the drums 9, 10' and 9' and 10' and .a coil 65 windable upon a drum 66.

corresponding coils are similar to the correspondingly numbered drums and coils of Fig. 1. The coil 8 leads through the brush 12, conductor 50 reactance 51 and conductor 52 to the grid of tube 53, while the coil 54 upon drum 55 leads through a brush 56, conductor 57 to the anode plate of the tube 53. A coil 58 on a drum 59 leads through a brush 60, conductor 61 reactance 62, conductor 63 to the grid of a tube 54, while the anode plate of tube is connected through a conductor 64 with Another coil 67 windable upon and from a drum 68 is connected through a reactance 69, a capacity 70 and a conductor 71 with the grid of a tube 72. The anode plate of the grid 72 is connected through a coupling transformer 73 with the grid of a tube 74, the anode of the latter being connected through a conductor 75 with the loud speaker 76. The coils 54, 58, 65 and 67 are windable and unwindable upon short circuiting drums 55, 59, 66 and 68', and thedrums 8, 59 and 68 are connected together through the conductor 77 and lead to the minus terminal of the A battery while the drums 55 and 66 are connected together through a conductor 78 and lead to the positive terminal to the B battery. The filaments of the tubes 53, 54, 72 and 74 are connected through the conductors 79 and 80 with the A bettery while one terminal of the coupling trancformer 73 leads to the positive side of the B battery and the other A and B battery connections are indicated by the corresponding letters and signs. The drums are mounted and geared together through a shaft 81 for simultaneous operation by the thumb knob 82.

In the modification of Fig. 3 the coils 85 and 86 are of the same diameter and wound and unwound upon the drums 87 and 88 of the same diameter, and similarly the short circuiting drums 87' and 88 are of the same diameter. Alsoccils 89 and 90 connected with the anode of the tube 3 are the same size, these coils being wound upon the drums 91 and 92 of the same size with the ratio of 1 to 1. Also, of course, the short circuiting drums 91' and 92' are likewise of the some diameter. The system otherwise corresponds generally to the system of Fig. l, a coup v 2'' being provided for inserting the loud speaker in position. The drum 92' is connected through a conductor 93' with a conductor 94 leading from one terminal of the A battery of the drum 9! and connected through a conductor 95 and a conductor 96 with one side of the B battery, the other side of the B battery being connected through a conductor 97 with the A battery. Theceuphng 2' is connected between the plus side of the B battery and the coil 31.

In Figs. 6 and 7 I have indicated a modified form of variable inductance and capacity drum, wherein the drum is provided with spiral grooves 100, the drum being of any suitable insulating material, as for example bakelite. The drum, of course, may be made of metal with the grooves duly insulated. In the bottom of the grooves is disposed a spirally wound flat plate as for example of aluminum flat plate or wire 191 forming the capacity plate while there is interposed between this, capacity plate 101 and the flexible conductor 42 of the variable coil insulating layers 102.

I claim:

1. In a radio transmitting and amplifying system the combination of detecting and amplifying devices and circuits with a variable reactance coil in one of the circuits comprising both variabk capacity and inductance and including a for and fieidble wire windable and unwindable about said form in a variable number of turns and means for winding and unwinding said wire, the means for winding and unwinding the wire comprising a pair of rotatable drums one being a short circuiting drum and the other having a capacity plate in electrical relation with the reactance coil.

2. In a radio system a variable inductance in the circuit including means for varying the length of the conductor forming the inductance coil, including a condenser plate in operative relation to the variable inductance coil.

3. In a radio transmitting and amplifying system the combination of detecting and amplifying devices and circuits with a variable reactance coil in one of the circuits comprising both variable capacity and inductance and including a form and flexible wire windable and unwindable about said form in a variable number of turns and means for winding and unwinding said wire, the means for winding and unwinding the wire comprising a pair of rotatable drums one being a short circuiting drum and the other having a capacity platein electrical relation with the reactance coil and of arcuate form closely surrounding the coil.

4. In a radio transmitting and amplifying system the combination of detecting and amplifying devices and circuits with a variable reactance coil in one of the circuits comprising both variable capacity and inductance and including a form and flexible wire windable and unwindable about said form in a variable number of turns and means for winding and unwinding said wire, the means for winding and unwinding the wire comprising a pair of rotatable drums one being a short circuiting drum and the other having a capacity plate in electrical relation with the reactance coil and of arcuate form closely surrounding the coil to give the desired relative capacity effect whereby by simultaneously rotating the drums the inductance and capacity of the circuit are simultaneously controlled and regulated without the necessity of a separate condenser in circuit.

MELVIN B. BENSON. 

